During an impassioned speech before hundreds of supporters, on the day his Atlanta campaign headquarters was supposed to open, Cain once again denied accusations and allegations of sexual harassment and an affair, calling them "false and unproven".

Monday, a Dunwoody woman, Ginger White, publicly alleged that she had carried on a 13-year, on and off affair with Cain.

Cain said the allegations and the ensuing media coverage had taken a toll on his wife and family. "That spin hurts," he said. "It hurts my wife. It hurts my family. It hurts me and it hurts the American people because you are being denied solutions to our problems."

With his wife of more than 40 years, Gloria, standing behind him, Cain remained defiant until the end. "I am at peace with my God. I am at peace with my wife and she is at peace with me," Cain said.

During the speech, Cain made reference to his humble upbringing in Atlanta. "When you think of where I came from on Pelham Street and the Fifth Ward in Atlanta, that's why this is a great nation," he said. "I am proof that the common man could lead this nation."

Cain said becoming President was "Plan A". He announced his "Plan B" moments after bowing out of the race for the GOP nomination.